The present invention refers to a device for screeding or trowelling a filling compound, especially concrete, and comprises a rotatable trowelling member, which is displaceable in the horizontal plane. When working with concrete, for instance when casting floors in buildings, and covering surfaces of roads and viaducts, it is desirable to be able to work a large area in a single operation, so requirements concerning strength and level finish within prescribed tolerances are fulfilled.
Conventional technique includes poker vibration of the compound, and then surface vibrations to obtain a smoothness of the surface. A surface vibrating apparatus usually comprises a frame carrying vibrator means, and having two spaced long scraper blades, which trowel the concrete surface. The frame is carried by rails and is mostly operated manually.
The rails may be formedby edge portions of the formwork, or by pipes resting upon specially erected supports, and must be carefully weighed out.
Trowelling of smaller surfaces is often made by means of manually operated machines, which instead of blades are provided with a rotatable disc. Such a machine is carried by the disc resting on the concrete, and it is necessary that the concrete has set to some degree before the operation starts. Also here the edge portions of the formwork must be carefully weighed out, as they are the only references available to the operator, which must have a high degree of skill and experience, so the surface become absolutely flat without "dips".